Well, the ISO 9141 is a service code of the scanner, it doesn't indicate any actual problem in your vehicle. It only means that there is something wrong with the communication between the car and the scanner. Also, it may show incompatibility of the scanner and problems with the electrical system of your vehicle not allowing the ECU to connect to the scanning tool.
ISO9141 code highlights
- Level of urgency:Low
- Possible culprits:Scanner isbadlyconnected or not compatible
- Price for repair:$0
- If neglected:No codes will be detected
- DIY repairs:Possible
- Can you drive?Yes
What are the possible reasons for the ISO 9141 code to appear?
First of all, you need to remember that this code doesn't show any actual problem with the vehicle. This is a code that is integrated into the diagnostic system of the code scanner itself and it basically shows that the scanner fails to communicate with the vehicle. So, the scanner actually sees that it's connected to something. But it doesn't see what it is and can't get any proper information.
Why may this happen? Well, I see several possible reasons for this issue:
1) The scanner is not properly hooked
If the connection between the scanner and the OBD2 port is not that good, the scanner will most likely throw this code. Try pressing it a little harder or see if the port is clogged with dust or something else. Also, make sure that the contacts on the scanner are not corroded.
2) There is no power
Another option is that you didn't turn on the ignition (without starting the engine) when you tried to read the codes. A lot of car owners will try to activate the scanning process when the car is off or in the accessory mode. You should turn the ignition on for the scanner to catch some codes.
3) Ground wire has a bad connection
One common thing that can trigger the ISO9141 code on your scanning tool is the bad ground wire. Locate the ground under the hood of your car, unscrew the cable, and clean the contact. Also, make sure that the wire hasn't been broken.
4) Wrong scanner
It's pretty common for car owners to get the improper scanner that just can't do the job they ask it to do. It may not be compatible with the car or may not do the function that you need. Also, the code may appear when the scanner can't reach the ECU because the ECU is blocked for certain types of scanners.
5) ECU problems
If the ECU is disconnected, your car will not start and no functions will work in it at all. Of course, if you plug in the scanner, it will show you the ISO 9141 code just because it can't locate any electronic control unit to communicate with.
6) The battery is completely dead
If the battery has too low voltage or is dead at all, your car modules will not get proper power to communicate with the scanner. Hence, the scanner will throw the code to let you know there is no ECU that it can "talk" to.
What can you do to deal with the problem?
I've already told you above about some ways to cope with it. Let's just quickly brush up on some recommendations:
- reconnect the scanner;
- check if the connections are clean;
- clean the ground cable;
- check the battery voltage;
- make sure you are doing things right;
- get another scanner to check things;
- go to a repair shop and ask them to scan the codes.
Sometimes, broken scanners will throw this code. There may be some problem with the connections in the scanner itself or it may have been fried. Unfortunately, this is not really uncommon for those cheap scanners that look like they are made to be used only once.
If you keep getting these strange codes on your scanner, you should ask for professional help. Never rely on the information from online forums because people just give their opinions and the majority of them are based on very narrow experience of dealing with car diagnostics.
About the authors
The CarAraC research team is composed of seasoned auto mechanics and automotive industry professionals, including individuals with advanced degrees and certifications in their field. Our team members boast prestigious credentials, reflecting their extensive knowledge and skills. These qualifications include: IMI: Institute of the Motor Industry, ASE-Certified Master Automobile Technicians; Coventry University, Graduate of MA in Automotive Journalism; Politecnico di Torino, Italy, MS Automotive Engineering; Ss. Cyril and Methodius University in Skopje, Mechanical University in Skopje; TOC Automotive College; DHA Suffa University, Department of Mechanical Engineering
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